The present disclosure relates to radio communication systems, and in typical radio communication systems, only one user can speak to subscriber units on a given channel/talkgroup at any time. An exemplary radio communication system can include a dispatch system with a dispatch console and one or more subscriber units. Conventionally, the dispatch console has priority on a given channel/talkgroup, i.e., if both the dispatch console and a subscriber speak simultaneously, dispatch console users can hear both, but other subscriber units only hear the dispatch console. In conventional analog radio communication systems, there was a desire to allow two users to speak simultaneously, e.g., if both the dispatch console and a subscriber speak simultaneously, dispatch consoles hear both speakers, and the two transmitted audio signals are summed together and sent to other subscriber units so they can also hear both speak. Summing two audio signals in the analog domain is well known in the art. Further, radio communication systems are moving towards digital implementations. For example, digital radio communication systems can be easily encrypted to prevent eavesdropping which is advantageous in public safety dispatch systems (e.g., police, fire, etc.). While digital audio can be summed, issues arise if the two originating voice streams are encrypted using different encryption parameters, including encryption modes, algorithms, or keys. Broadcasting an originating audio stream in a summed digital audio stream using a non-originating audio stream encryption mode and/or key may allow non-intended users to hear the audio from the originating audio stream.
Accordingly, there is a need for audio summing systems and methods in radio communication systems.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.